if exists(select * from sysobjects where name=约束名) alter table 表名 drop constraint 约束名; go alter table 表名 add constraint 约束名 check(约束规则),constraint 约束名 check(约束规则); go 示例: -- 添加一个默认约束 use testss; go if exists(select * from sysobjects where name='check1...
try this SQL 2005+ EXECUTE master.sys.sp_MSforeachdb 'USE [?]; if exists(select * from INFORMATION_SCHEMA.tables where TABLE_TYPE=''BASE TABLE'' and TABLE_NAME=''DB_BACKUP_LOG_T'') begin print ''exist in '' + db_name() end' SQL 2000 EXECUTE master.dbo.sp_MSforeachdb ...
if exists(select * from sysobjects where name=约束名) alter table 表名 drop constraint 约束名; go alter table 表名 add constraint 约束名 check(约束规则),constraint 约束名 check(约束规则); go 示例: -- 添加一个默认约束 use testss; go if exists(select * from sysobjects where name='check1...
September 24, 2009, 5:38 pm Simple question, simple answer SQL Query to return the data ? 1 SELECTTABLE_NAMEFROMDBName.INFORMATION_SCHEMA.TablesWHERETABLE_NAME='Article' How do I check this in C#? As for how you check that in C#? You just make sure the Row count returned from the qu...
Example: IFEXISTS(SELECT1FROMsys.ObjectsWHEREObject_id=OBJECT_ID(N’dbo.Image’)ANDType=N’U’)BEGINPRINT‘TableExists’ENDIFEXISTS(SELECT1FROMsys.TablesWHEREName=N’Image’ANDType=N’U’)BEGINPRINT‘TableExists’END 是为之记。 Alva Chien ...
在查询分析器里边执行alter table 表名drop constraint 约束名查看表的约束名执行sp_...
在MySQL 8.0.16以前,CREATE TABLE允许从语法层面输入下列CHECK约束,但实际没有效果: CHECK (expr) 1. 在MySQL 8.0.16,CREATE TABLE添加了针对所有存储引擎的表和列的CHECK约束的核心特性。CREATE TABLE允许如下针对表或列的约束语法: [CONSTRAINT [symbol]] CHECK (expr) [[NOT] ENFORCED] ...
使用T-SQL脚本添加CHECK约束 当表结构存在时 添加CHECK约束时首先校验约束是否已存在,如果存在应该是先删除再添加,如果不存在则直接添加。 语法: -- 添加一个默认约束 use 数据库名; go if exists(select * from sysobjects where name=约束名) alter table 表名 drop constraint 约束名; ...
EXISTS is used in a WHERE clause of a main query, so it won't work on its own like that. However, if you simply want to know if a record exists in a table, you could also use either the DLookup() or DCount() function. For example: ...
Check if database table exists with JDBC JDBC (Java Database Connectivity) is a Java API that enables Java applications to connect to and interact with databases. JDBC provides a standard set of Java classes and interfaces that enable Java programs to ac